1. Field of the Invention
The present invention relates to a resilient prosthetic foot that has a reinforcement member to provide reinforcement. More particularly, the present invention relates to a prosthetic foot having at least a resilient forefoot member, and at least one resilient reinforcement member.
2. Related Art
Many individuals have lost a limb for various reasons including war, accident, or disease. In most instances these individuals are not only able to live relatively normal lives, but physically active lives as well. Often times, these individuals are aided in their everyday lives by a prosthetic limb. The objective of prosthesis is to provide an artificial limb that simulates the function and natural feel of the replaced limb.
With respect to prosthetic feet, the development of a functional and natural artificial foot has been limited only by material and imagination. Many designs have attempted to copy the anatomy of the foot or simulate its actions by replacing the bones and muscle with various mechanical components. Other designs have departed radically from mere anatomical copying or mechanical simulation by replacing the entire foot with an energy storage element, such as a spring. For example, see U.S. Pat. No. 4,547,913 or 5,593,456. As the user steps onto the foot, the user's weight compresses the spring. As the user moves forward, the user's weight comes off the foot and the energy stored in the spring is used to propel the user forward.
The stiffness of prosthetic feet typically varies according to the intended use. Feet intended for everyday use typically require a soft feel, and thus incorporate a loose spring. Feet intended for athletic use typically require strength, and thus incorporate a stiff spring. Although different prosthetic feet may be changed to suit the particular activity, such switching is inconvenient and at times it is impossible, such as a sudden need to run to catch, or avoid being hit by a bus. Feet designed for particular purposes are typically unsuited for other purposes. Stiff, athletic feet are too hard for everyday use, and loose, everyday feet are too fragile for athletic use. Multiple-use feet have been designed which are capable of many different uses, but without being particularly well suited for any use.
In addition, the performance of these energy storing feet has been altered in various ways to provide a more universal foot which is capable of many different uses ranging from athletic use to more normal walking. For example, some feet use multiple springs, bladders or resilient materials disposed between various elements, and/or multiple springs that deflect at different intervals of foot deflection in order to increase resistance as the force applied to the foot by the user increases. In this way, a prosthetic foot can provide a stiff or highly resilient response when a high load is applied, such as when the user runs, or a looser less resilient response when a lower load is applied, such as when the user walks. For example, see U.S. Pat. No. 6,241,776 or 6,099,572, both of which propose multiple members; one of which disposes an adjustable pressure buffer between members; the other of which places a secondary member in the extreme range of motion of a primary member.
While many prosthetic feet have been designed to accommodate variation in terrain and use, there is still a need to increase the amount of energy a prosthetic foot can store during use which can be returned to the user to help propel the user forward.